A number of countries have banned Boeing's 737 MAX 8 medium-haul workhorse jet from their airspace in response to the Ethiopian Airlines crash that killed all 157 people on board.

Several airlines have grounded the 737 MAX 8 aircraft in their fleets, but many others are continuing to fly the plane pending an investigation into the crash and possible guidance from Boeing itself.

Even airlines still operating the model have been restricted by the action. Air Canada, for example, was obliged to cancel some flights to London because of Britain's ban on the aircraft.

The Nairobi-bound plane was the same type as the Indonesian Lion Air jet that crashed in October, killing 189 passengers and crew -- and some officials have detected similarities between the two accidents.

More than 370 of the 737 MAX 8 planes are in service around the world, with nearly 5,000 on order.